MAIDUGURI, Nigeria -- Residents and officials say a suicide bomber has killed himself and 16 others outside a mosque in the Nigerian city Maiduguri.

Trader Ali Bakomi said the bomber was pushing a wheelbarrow and then joined a crowd of people in front of the mosque in the biggest city in Nigeria's troubled northeast.

Officials told Borno state Gov. Kashim Shettima that the bomber killed himself and 16 other people.

The bombing came hours after rocket-propelled grenades exploded into homes before dawn. They killed at least 13 people and injured more, according to resident Idrissa Mandara.

A multinational offensive this year has forced the insurgents from towns where they had declared an Islamic caliphate but suicide bombings and hit-and-run attacks continue.